1. Field of the Invention
The present invention relates to a draining and drying apparatus of semiconductor material, and more particularly to the art of drying semiconductor materials such as semiconductor silicon wafers and glass photo masks. Water drops (draining) of cleaning solution existing on the semiconductor materials are removed using the centrifugal force action of a so-called spindle dryer after the semiconductor materials are treated in a series of processes including an etching process, a resist peeling process, etc. and related cleaning processes.
2. Description of the Related Art
Generally, in wet treating process of semiconductor materials, generally, semiconductor materials are grouped together by a specific number of pieces, and sequentially treated in a series of treating processes including etching process, resist peeling process, etc. and related cleaning processes, and finally drained and dried.
That is, a cassette (also known as carrier) accommodating a specific number of semiconductor materials is sequentially conveyed in a series of treating process steps comprising etching step, resist peeling step, etc. and related cleaning steps, and is finally conveyed to the drying step to be dried by the draining and drying apparatus.
Hitherto, various structures have been known for such draining and drying apparatus. A general structure of these apparatuses is to make use of the centrifugal force action of a spin dryer, and comprises a rotor driven at high rotating speed, a rotor casing enclosing the rotor, and a pair of cradles disposed on the rotor oppositely across the center of rotation for accommodating a specific number of semiconductor materials to be dried.
Two cassettes are set in the cradles on the rotor, and the rotor rotates at high speed, and the semiconductor materials in the cassette accommodated in the cradles are turned about the center of rotation of the rotor, and water drops of cleaning solution existing on the semiconductor materials are removed by the centrifugal force generated at this time, thereby draining and drying.
The cassettes containing a specific number of semiconductor materials are automatically conveyed by a conveying device (a onveying robot) in a series of treating steps including etching step, resist peeling step, etc. and related cleaning steps, and finally in the draining and drying step, and the number of semiconductor materials contained in the cassettes are automatically counted by the conveying device, and the result of counting is sequentially sent and processed in a central control part provided in each step, that is, the central processing unit.
Recently, however, the manner of use of the draining and drying apparatus varies depending on the users, and the conventional structure involves the following problems, of which improvements have been demanded.
That is, although two cradles for receiving the cassettes are disposed on the rotor of the apparatus, various manners of use existed, for example, (1) only one cradle accommodated a cassette containing a specific number of semiconductor materials, or (2) a cassette containing a specific number of semiconductors was put in one cradle, while a cassette containing less than a specific number of semiconductor materials was put in the other cradle.
In such case, therefore, it is necessary to adjust the balance of rotation of the rotor. In the former case, for instance, a cassette containing a specific number of dummy semiconductor materials must be put in the other cradle, or in the latter case, the cassette containing less than a specific number of semiconductor materials must be filled with dummy semiconductor materials for cover up for the shortage. All these filling works must be done manually, which not only lowers the processing efficiency in the drying process, but also brings about various problems in the flow of a series of processes.